**7.** *Clostridium*

*Clostridium* is a genus of bacteria that include more than 100 species, is categorized as a Gram-positive bacterium, has flagella, and is anaerobic. They can cause multiple foodborne diseases in humans, such as botulism, *C. perfringens* food poisoning, necrotizing enteritis, and others [5]. These microorganisms can sporulate, which increases their resistance, and they can spread through abiotic surfaces.

In addition, some species can form biofilms, which are beneficial in some industrial processes (recycling and cellulose degradation processes, gas, acetone, butanol, and ethanol production) [5, 79, 80]. There are also some non-pathogenic bacteria in humans that form this type of biofilm and are part of the intestinal microbiota, such as *Clostridium clostridioforme* and *Clostridium malenominatum* [5].

In the case of pathogenic bacteria that cause diseases in humans, biofilms produced from bacteria can be a significant issue because this mechanism protects the microorganisms from antibiotics, the environment, toxic molecules, certain stress conditions, and immune system responses, hence, biofilm helps bacteria survive and may play a role in virulence [5, 6].

Specifically, the *Clostridium* species transmitted by food contamination that causes virulence in humans with the ability to form biofilms are *C difficile*, *C. botulinum,* and *C. perfringens* [5].

*C difficile. Clostridium difficile* infections (CDI) from *C. difficile* are the most prevalent cause of nosocomial diarrhea and colitis in the United States [81, 82]. This species develops in the colon after antibiotic medication changes the gut microbiota and secretes toxins that are virulence factors, including A and B toxins [80, 81, 83].

*C. botulinum.* These species produce one of the most lethal substances known to induce botulism, botulinum neurotoxin (BoNT). Botulinum toxin inhibits nerve function and can induce paralysis of the respiratory and muscular systems [84].

*C. perfringens*. One of the most common causes of foodborne infection in the United States. It can produce numerous toxins and is the cause of gas gangrene, necrotizing enteritis, food poisoning, and diarrhea associated with antibiotics [6].

#### **7.1 Quorum sensing related genes and nanosystems' evaluation**

Into the *Clostridium* genus, the implicated QS genes of *C. perfringens* are well established. QS is performed by the Agr and LuxS systems that are involved in toxin production and pathogenicity through propeptides and AI-2 production, respectively [85]. Although CDI have been widely reported and associated with *C. difficile* toxin production, the QS system by which these infections are regulated is considered a

*Nanosystems as Quorum Quenchers Targeting Foodborne Pathogens: Understanding… DOI: http://dx.doi.org/10.5772/intechopen.112266*

complex multifactorial process [86]. There are even few reports on the effect of nanosystems involved in biofilm and QS inhibition in *Clostridium.*

In a study, Omoigberale, see [87], it has been found that Ag-NPs at a concentration of 10 mgmL<sup>1</sup> can generate a biofilm reduction of 19–58%, while Au-NPs generate a smaller reduction with 12–39%, at the same concentration. However, this percentage range of reduction is considered strain-dependent, since this behavior was evaluated in 17 strains of *Clostridia.* At the same time, Au-NPs/Ag-NPs-Gentamicin complexes were evaluated obtaining 31% and 30% biofilm reduction, respectively. Although it was not a better performance than that obtained for the simple metallic nanoparticles, it did have a better effect compared to other antibiotics tested in the nanosystems.

Silver nanoparticles (Ag-NPs) also have been evaluated on specific isolates of *C. perfringens*, finding biofilm inhibition percentages of 80.8–82.8% at concentrations up to 100 <sup>μ</sup><sup>g</sup>mL<sup>1</sup> , but showing the same behavior as in previous studies [87] in which these percentages are strain-dependent, or in this case, isolate-dependent from different animal and human organisms [88].

Undoubtedly, the molecular study of nanosystems with inhibitory QS potential is a great area of opportunity for this genus, pursuing to elucidate the signaling mechanisms and QQs that could counteract its pathogenicity.

#### **8. Conclusions and perspectives**

Biofilm formation is nowadays a worldwide topic of interest for public health due to the importance in pathogen survival. Knowing the mechanism of synthesis can help to develop new materials to prevent and eliminate bacteria. Quorum sensing is one of the mechanisms through which bacteria can communicate and create barriers against antibacterial agents. Nanosystems applied in food safety may interact with genes that express the signalization of quorum sensing, as many authors have reported. Understanding the interaction of the nanoparticle with the DNA of cells may lead to the formulation of new materials that exhibit this inhibition route, and for that, molecular docking can help to elucidate the possible interaction and, further, allow the food industry to be even safer for all populations.

#### **Acknowledgements**

The authors express their gratitude to the Mexican National Council of Science and Technology (CONACYT) for their support under the grant number 973558 throughout the Doctoral program in Sciences in Biotechnological Processes of the Universidad de Guadalajara.

#### **Conflict of interest**

The authors declare no conflict of interest.

#### **Notes/thanks/other declarations**

The authors state that there are no other declarations.
